#Requires -Modules @{ ModuleName = 'Pester'; ModuleVersion = '5.0.0' }

<#
    FR-004: @odata.nextLink is followed to exhaustion, and a truncated enumeration
    raises rather than returning a partial population.

    The second half is the one worth the effort. A partial population reconciles
    cleanly, produces a plausible summary, and reports success - so nothing
    downstream can tell that half the tenant was never looked at.
#>

BeforeAll {
    $repoRoot = Split-Path (Split-Path $PSScriptRoot -Parent) -Parent
    . (Join-Path $repoRoot 'tests/TestHelpers.ps1')
    foreach ($file in (Get-PersonaSourceFile -RepoRoot $repoRoot)) { . $file }

    $script:target = 'extension_<EXTENSION-APP-ID>_<PERSONA>'
}

Describe 'User enumeration pagination (FR-004)' {

    It 'follows nextLink across every page' {
        $script:page = 0

        Mock Invoke-PersonaGraphRequest {
            $script:page++
            $users = 1..3 | ForEach-Object {
                New-TestGraphUser -Id ('00000000-0000-0000-0000-{0:d12}' -f (($script:page - 1) * 3 + $_)) `
                    -UserPrincipalName ("user{0}-{1}@example.invalid" -f $script:page, $_)
            }

            $response = @{ value = $users }
            if ($script:page -lt 4) { $response['@odata.nextLink'] = "/v1.0/users?`$skiptoken=page$script:page" }
            $response
        }

        $result = @(Get-PersonaUsers -SelectProperties @('id', 'userPrincipalName'))

        $result.Count | Should -Be 12
        Should -Invoke Invoke-PersonaGraphRequest -Times 4 -Exactly
    }

    It 'stops when nextLink is absent rather than looping' {
        Mock Invoke-PersonaGraphRequest { @{ value = @(New-TestGraphUser -Id '00000000-0000-0000-0000-000000000001' -UserPrincipalName 'a@example.invalid') } }

        $result = @(Get-PersonaUsers -SelectProperties @('id'))

        $result.Count | Should -Be 1
        Should -Invoke Invoke-PersonaGraphRequest -Times 1 -Exactly
    }

    It 'raises on a response with no value collection rather than returning what it has' {
        $script:page = 0

        Mock Invoke-PersonaGraphRequest {
            $script:page++
            if ($script:page -eq 1) {
                return @{
                    value            = @(New-TestGraphUser -Id '00000000-0000-0000-0000-000000000001' -UserPrincipalName 'a@example.invalid')
                    '@odata.nextLink' = '/v1.0/users?$skiptoken=abc'
                }
            }
            # Page two comes back malformed. Returning page one alone would look like
            # a complete, tiny tenant.
            @{ error = 'unexpected' }
        }

        { @(Get-PersonaUsers -SelectProperties @('id')) } | Should -Throw -ExpectedMessage '*partial population*'
    }

    It 'raises on a null response' {
        Mock Invoke-PersonaGraphRequest { $null }

        { @(Get-PersonaUsers -SelectProperties @('id')) } | Should -Throw
    }

    It 'requests the maximum page size so a large tenant needs fewer round trips' {
        Mock Invoke-PersonaGraphRequest -ParameterFilter { $Uri -match '\$top=999' } -MockWith { @{ value = @() } }

        $null = @(Get-PersonaUsers -SelectProperties @('id'))

        Should -Invoke Invoke-PersonaGraphRequest -Times 1 -Exactly
    }
}

Describe 'Membership pagination' {

    It 'follows nextLink and collects only group objects' {
        $script:page = 0

        Mock Invoke-PersonaGraphRequest {
            $script:page++
            if ($script:page -eq 1) {
                return @{
                    value             = @(
                        @{ '@odata.type' = '#microsoft.graph.group'; id = '00000000-0000-0000-0000-0000000000a0' }
                        # An administrative unit arriving on memberOf. Treating it as
                        # a group ID would never match, which reads as "not a member".
                        @{ '@odata.type' = '#microsoft.graph.administrativeUnit'; id = '00000000-0000-0000-0000-0000000000e0' }
                    )
                    '@odata.nextLink' = '/v1.0/users/x/memberOf?$skiptoken=abc'
                }
            }
            @{ value = @(@{ '@odata.type' = '#microsoft.graph.group'; id = '00000000-0000-0000-0000-0000000000b0' }) }
        }

        $record = Get-PersonaGroupMembership -UserObjectId '00000000-0000-0000-0000-000000000101' -NeedDirect

        $record.DirectRetrieved | Should -BeTrue
        $record.DirectGroupObjectIds.Count | Should -Be 2
        $record.DirectGroupObjectIds | Should -Contain '00000000-0000-0000-0000-0000000000a0'
        $record.DirectGroupObjectIds | Should -Contain '00000000-0000-0000-0000-0000000000b0'
        $record.DirectGroupObjectIds | Should -Not -Contain '00000000-0000-0000-0000-0000000000e0'
    }

    It 'contains a mid-pagination failure to the affected facet instead of returning a short list' {
        # The critical case. A truncated membership list looks exactly like a user who
        # left a group, and would silently reclassify them (FR-013).
        Mock Invoke-PersonaGraphRequest { throw 'Graph 503 after 5 attempts' }

        $record = Get-PersonaGroupMembership -UserObjectId '00000000-0000-0000-0000-000000000101' -NeedDirect

        $record.DirectRetrieved | Should -BeFalse
        $record.DirectFailureReason | Should -Not -BeNullOrEmpty
    }
}